Lake Brook Trout Research Articles

Thermal habitat of Brook Trout in lakes of different size

AbstractWe assessed thermal habitat use of lake-dwelling Brook Trout (Salvelinus fontinalis) populations in 39 lakes of varying size with short-set duration, stratified-random netting surveys in Al...

Modeling Brook Trout Carrying Capacity in Owhi Lake, Washington, Using Bioenergetics

AbstractThe management of fish populations often requires an understanding of how density‐dependent effects influence population dynamics. In systems where natural populations are supplemented with stocking, the question of “how much food is available” becomes increasingly important. One typical approach for assessing density‐dependent interactions is to identify disparities between fish consumption rates and food availability. The objective of our study was to determine whether seasonal lake prey production could support Brook Trout Salvelinus fontinalis consumption demand in Owhi Lake, Washington, at observed abundances. Brook Trout were collected seasonally from 2015 to 2017 to obtain information on length, weight, age, diet, growth, and mortality. Population abundance was estimated in summer by using hydroacoustic surveys. Littoral invertebrates and pelagic zooplankton were collected concurrently with fish to enumerate biomass and production. Bioenergetics modeling was used to estimate prey consumption by Brook Trout. In conjunction with supply–demand comparisons, we used growth efficiencies and maximum consumption rates to further identify potential seasonal and annual food limitations. Our results suggest that prey production could support Brook Trout consumption demand for all years, but littoral invertebrate consumption was close to or exceeded prey production in summer and fall 2017. Growth efficiency was lowest and maximum consumption rates were highest in summer 2017 relative to all other seasons and years. In addition to observed diet switching from littoral invertebrates to zooplankton in summer 2016 and 2017, we concluded that lower growth efficiencies, lower annual survival rates, and increased consumption rates were influenced by littoral invertebrate production. The Owhi Lake Brook Trout stocking program may require adaptive management (i.e., annual evaluations) to balance natural recruitment.

Evaluating the Ability of Tiger Muskellunge to Eradicate Brook Trout in Idaho Alpine Lakes

AbstractIn western North America, nonnative Brook Trout Salvelinus fontinalis in alpine lakes threaten the persistence of native trout and often offer limited sport fishing opportunity as they are prone to stunting. Stocking tiger muskellunge (Northern Pike Esox lucius × Muskellunge E. masquinongy), which are reproductively sterile, may be an option to eradicate Brook Trout in some alpine lakes. We used floating gill nets to survey 17 alpine lake Brook Trout populations, then stocked 13 lakes with tiger muskellunge, with four additional lakes serving as controls. Tiger muskellunge were stocked at a mean TL of 317 mm and a density of 40 fish/ha. Brook Trout were resampled for 4 or 5 years after stocking to evaluate changes in Brook Trout TL and CPUE (fish/net‐night). Declines in CPUE were substantial for both treatment and control lakes but were significantly greater in treatment lakes. Mean Brook Trout CPUE in treatment lakes declined from 23.1 fish/net‐night to 2.3 fish/net‐night 5 years after stocking tiger muskellunge, whereas in control lakes, CPUE declined from 25.5 fish/net‐night to 7.8 fish/net‐night 5 years later. Complete eradication appeared to occur in two lakes within 2 years, and in two more lakes by year 5. In lakes where tiger muskellunge were stocked, the proportion of Brook Trout ≥250 mm TL in the catch increased significantly in years 1, 2, and 4 after stocking (compared with prestocking data), whereas no increase occurred in control lakes. Tiger muskellunge were most successful in reducing Brook Trout CPUE in lakes with no inlets or outlets, while elevation and lake area may also have played a role. Our results suggest tiger muskellunge can improve the size structure and potentially eradicate Brook Trout populations from some alpine lakes. However, we recommend combining any tiger muskellunge stocking with other conventional removal methods to increase the likelihood of successful eradication.Received October 27, 2014; accepted March 22, 2015

Shifts in the Trophic Ecology of Brook Trout Resulting from Interactions with Yellow Perch: An Intraguild Predator‐Prey Interaction

AbstractIn size‐structured populations, predator‐prey interactions may be preceded by a phase of resource competition earlier in ontogeny, with potential consequences for population dynamics and resource management. We hypothesized that brook trout Salvelinus fontinalis and yellow perch Perca flavescens would compete for shared resources and interact as predator and prey. We used stable isotopes and stomach content analysis to compare the trophic ecology of brook trout in lakes with and without yellow perch. Percent littoral resource use by brook trout differed between perch and nonperch systems, ranging from approximately 50% to 100% in nonperch lakes compared with 10‐70% in perch lakes. Nonpiscivorous‐sized brook trout (fork length [FL] < 25 cm) showed a significant ontogenetic diet shift toward greater pelagic resource use during growth from 15 to 25 cm in sympatry with yellow perch. Nonpiscivorous‐sized brook trout in nonperch lakes consumed a mixture of zoobenthos, zooplankton, and littoral prey fish. In contrast, in lakes containing yellow perch, nonpiscivorous‐sized brook trout fed primarily on pelagic prey. Brook trout shifted to piscivory at a FL of approximately 25 cm in both perch and nonperch systems. Isotopic results and stomach content analysis indicated that yellow perch were the primary prey of piscivorous‐sized brook trout (FL > 25 cm) in perch lakes, occurring in 66‐100% of the brook trout sampled and accounting for over 97% of the diet by weight. Overall, the presence of yellow perch resulted in a shift in the energetic basis for brook trout production from primarily littoral to primarily pelagic. The shift in brook trout food web position was associated with a decline in brook trout catch per unit effort. We conclude that brook trout and yellow perch interact as intraguild predator and prey and that the interaction is dominated by yellow perch.

Ecology, Evolution, and Conservation of Lake‐Migratory Brook Trout: A Perspective from Pristine Populations

AbstractReintroduction or rehabilitation plans for fish populations in many systems (e.g., lakes) are complicated by limited data on ecological and genetic characteristics before human disturbances occurred. While no two lakes have identical physical and biological characteristics, a growing body of empirical evidence nevertheless indicates that parallel patterns of population structuring may evolve within northern temperate fish species. Examining the population structuring in undisturbed lakes of similar physical and biological characteristics may thus provide insight into the probable historical extent and causes of both population structuring and connectivity in human‐impacted lakes. Here, we review research on the population structuring and evolution of migratory brook trout Salvelinus fontinalis in a relatively undisturbed, postglacial lake (Mistassini Lake, Quebec). We provide information on lake habitat use, the morphology and life history characteristics of populations, diets, lakewide genetic population structure, seasonal migration characteristics between spawning and feeding areas, population evolutionary histories, and the prevalence of lake spawning. The biology of Mistassini Lake brook trout has a compelling number of similarities with what is known about that of the “coaster” form in Lake Superior and lake‐migratory brook trout elsewhere. Our review also has several implications for the rehabilitation of coaster populations with respect to (1) clarifying the degree of natural connectivity between populations; (2) predicting the likelihood of recolonization of vacant habitats; (3) choosing candidate source populations for translocations; and more broadly, (4) understanding the spatial scale of probable local adaptation. Mistassini Lake therefore provides a useful case study that applies to lake‐migratory trout elsewhere. We hope that our research will stimulate managers and biologists working on similar systems with pronounced human disturbances to consider the interplay between ecology and evolution in future conservation efforts.

Diffusion in the littoral zone: scoping emergence times and movement to essential habitat for young‐of‐year brook trout in lakes

Factors governing the process of dispersal of lake‐spawned brook trout (Salvelinus fontinalis) young‐of‐year (YOY) appear drastically different from those governing dispersal in more commonly studied stream salmonids. Rather than dispersal being highly density‐dependent and the result of territoriality and aggression, in brook trout it may be density‐independent and driven by a common need for coldwater habitat for summer survival. Emerging fish travel great distances from single spawning sites on lakes to cold groundwater habitat. Movement is a gradual, one‐dimensional diffusion around lake margins and represents a very unique and simplified natal dispersal pathway allowing for dispersal rates, distances, and factors controlling these parameters to be measured. We predicted timing of the emergence period for brook trout alevins from lake spawning sites using the known relation between water temperature and emergence times for salmonids. Emergence and dispersal was then observed in the field by visually estimating YOY density in segments of the littoral zone throughout the dispersal period. Fluxes in density in these sections were used to estimate rate of YOY spread. YOY behaviour and body condition was also assessed across the wave of spatial spread. We are working towards a spatially explicit model to identify critical groundwater rearing habitat needing protection from forestry activities.

Response of fish communities to different levels of white sucker (Catostomus commersoni) biomanipulation in five temperate lakes

The goal of this study was to evaluate the response of white sucker (Catostomus commersoni), brook trout (Salvelinus fontinalis), and other fish species to the mass removal of white sucker in five Québec (Canada) lakes. White sucker removal ranged from 14.2 kg·ha–1 to 31.3 kg·ha–1 3 years after mass removal. In four of the study lakes, the proportion of 2+ to 4+ white sucker increased following mass removal. Mean catch and biomass per unit of effort of 1+ brook trout increased significantly in the lakes where white sucker removal was highest. All white sucker populations experienced growth increases after mass removal, and improved brook trout growth was observed in lakes where the most intensive mass removal occurred. These growth increases led to higher mean length at maturity in white sucker females and decreases in mean age at maturity in white sucker males and brook trout males and females. Mean adjusted fecundity significantly increased in white sucker and brook trout in lakes where mass removal was most intense. The present study suggests that white sucker and brook trout exhibit compensatory responses following a reduction of intra- and inter-specific competition and that these responses are related to the intensity of mass removal.

Population dynamics of brook trout (Salvelinus fontinalis) during maintenance liming of an acidic lake

Maintenance liming of an acidic lake in the Adirondack Mountains of New York state (Woods Lake) was conducted three times over a 5 yr period in an attempt to establish a self maintaining brook trout population. Various strains and age classes of marked brook trout were stocked annually and the population was inventoried semi annually to evaluate survival, growth, and reproductive success. The Woods Lake brook trout population was dominated by young, stocked fish throughout the maintenance liming period of 1985-89. Based on spring emergent fry trap catches and fall trap net catches of unmarked fish, only one naturally produced year class (1986) was successfully recruited to the Woods Lake brook trout population. Low annual survival rates (G 20%) of juvenile trout were observed throughout the study period. Although initial growth rates and condition of young trout were satisfactory, increased intraspecific competition for food resulted in declining growth rates and condition of older age classes. Fall standing crops of brook trout remained at relatively low levels of 6 to 10 kg ha−1 and both production per unit biomass and growth efficiency decreased over the 5-yr. Repeated whole lake liming and limited spawning habitat improvement were not sufficient to sustain brook trout natural reproduction in Woods Lake. Low productivity, marginal spawning habitat quality, and low survival rates of stocked trout in Woods Lake resulted in the failure to establish a self maintaining, productive brook trout population in Woods Lake.

Predicting acidification effects on fish populations, using laboratory data and field information

We developed a framework of linked models that uses lake levels of pH, Al, and Ca to predict the occurrence of fish species on a regional scale. As a first step, statistical models are fitted to laboratory data on brook trout (Salvelinus fontinalis). The resulting functions predict mortality and reduction in fecundity resulting from chemical conditions (pH, Al, and Ca). The second step applies a life-cycle model to results from the first step to estimate the reproductive potential expected for fish living in lakes with specified chemical conditions relative to that expected for fish living under nonstressful chemical conditions. Use of the framework requires field data on the presence or absence of brook trout in lakes having measured pH, Al, and Ca. The chemical conditions for each lake are processed through the first two steps to estimate the relative reproductive potential for brook trout in that lake. After, obtaining estimates for all lakes, a logistic regression model is fitted, with probability of occurrence as the dependent variable and relative reproductive potential as the independent variable. The resulting function, representing the calibrated framework, relates the probability of brook trout occurrence in high-elevation Adirondack (New York) lakes to relative (i.e., reduced) reproductive potential attributable to chemical stress. This function, when tested against additional data, can be used to predict changes in brook trout population status in relation to changed chemical conditions, stocking, or altered fishing pressure.

Semiannual Estimates of Natural Mortality of Hatchery Brook Trout in Lakes

Abstract Mark-and-recapture estimates of the number of hatchery-reared brook trout (Salvelinus fontinalis) have been made each April and October since October 1956 in Ford Lake (10 acres) and Hemlock Lake (6 acres), at the Pigeon River Trout Research Station, Vanderbilt, Michigan. Fish were captured by angling, by trapping with wire traps, and by shocking with direct current at night with underwater lights. A permit-type creel census insured a nearly complete record of the catch. Instantaneous mortality rates and conditional mortality rates were calculated for each year class. The largest natural loss of trout occurred during the first summer after planting. The rate of natural mortality during summer decreased with a decrease in the number of trout present each spring. Overwinter loss was negligible. The causes of the mortality are unknown.

Further Results from Spring and Fall Plantings of Legal-Sized, Hatchery-Reared Trout in Streams and Lakes of Michigan

Further tagging experiments in Michigan with spring and fall plantings of brook trout (Salvelinus f. fontinalis, brown trout (Salmo trutta), and rainbow trout (Salmo gairdnerii irideus) from which recoveries were made during the 1942 trout season confirmed the conclusion that spring release of adult or near adult hatchery-reared brook trout and rainbow trout is more desirable than the fall planting of fish of a similar size. In some instances fall stocking of brown trout may furnish as good fishing in the following seasons as does spring planting. Recoveries of planted fish past the first season of availability ranged from 0.0 to 2.5 per cent in the second season and from 0.0 to 0.5 per cent in the third season. In either spring or fall planting of legal-sized fish, no advantage was gained by scattering the fish widely over the stream areas stocked. Eighty five per cent or more of the planted trout recovered were caught within 10 miles of the point of release, regardless of the season or method of planting. Brown trout moved the least and rainbow trout the most. About one-fourth of the brook trout tended to move 3 to 10 miles downstream, and the majority of the remainder were caught within 3 miles of the locality of release. More rainbow trout than any other species were recaptured 10 or more miles from the point of release. Fall plantings of adult brook trout in lakes were recovered at the rate of 56.7 per cent (range, 13.0 to 88.1 per cent). Unfortunately, a small percentage of the anglers removed an average of 89.4 per cent of the total catch during the opening weeks of the trout season. The average recovery from two spring plantings of brook trout in East Fish Lake in Michigan was 68.5 per cent. A brief review of the literature substantiates the conclusions reached as a result of the Michigan experiments. Differences in experimental procedure are pointed out, and some reasons are offered for the failure of fish planted in streams in the fall to survive the winter season.